1. Field of the Invention
The invention relates generally to sensors that produce an output indicating pressure and position and more specifically to that class of position sensors known as tactile sensors which provide information on the local geometry of a surface.
2. Description of the Prior Art
Tactile sensors are generally known and can be grouped into a number of different categories depending upon their construction, the most common groups are piezoresistive, piezoelectric, capacitive and elastoresistive structures. The common feature of all of these devices is the transduction of local asperities (unevenness or a projection from a surface) into electrical signals. Tactile sensors are commonly used in the field of robotics and in particular with those robotic devices which pick up and place objects in accordance with programmed instructions; the so-called "pick and place" class of robot. Unfortunately, while it would be desirable for the above-listed groups of tactile sensors to respond in much the same way that the human finger does, many of them can provide only limited information about a contact with an object. This requires large numbers of separate structures or electrical characteristics that require extensive circuitry in order to obtain an output indicative of the surface which has been contacted. For robotics, the difficulties associated with their non-linear response mechanisms, their fragile structure and the high cost of assembling many discrete components limits their use of the above groups in an industrial environment. And if their use is not prohibited, there are difficulties with calibration, environmental survivability, etc. which render them less than optimum for the application.